Locating and/or tracking a person or an object in an indoor space or a confined area is typically referred to as indoor positioning, indoor localization, local positioning and the like. Indoor positioning is used for many applications such as locating or giving directions to tourists in an exhibition, locating doctors/nurses/medical equipment in a hospital, locating personnel as well as containers/merchandise in a large warehouse and the like.
Systems employed for indoor positioning, as known in the art, are typically based on inertial navigation wherein these systems generally incorporate technologies such as Global Positioning System (GPS) based tracking, wireless/WiFi tracking using Radio Frequency (RF) communication and typically use sensors such as gyroscopes, accelerometers and electromagnetic field sensors for location detection. Typically a wireless communication device carried by a person or affixed onto an object, sends out wireless signals which are picked up by sensors placed at different locations within the indoor environment and used for locating and/or tracking the person/object. Some systems use beacons embedded in wireless communication devices that transmit/broadcast signals which are picked up by WiFi receivers placed at different locations in the indoor environment and are used to locate the person/object by mapping the indoor environment or via the GPS. Other systems use RFID tags affixed onto the object or carried by the person while moving around in the indoor environment. The RFID tags are detected by sensors placed at different locations when the person/object passes near the sensor whereupon the sensor signals are used to locate the person/object.
Several endeavors have been made in this field for localizing a moving person/object. For instance, U.S. Pat. No. 6,393,360 discloses a method of outdoor localization. WO/2013/065042 discloses a method of both indoor and outdoor localization using earth magnetic field readings and electromagnetic signals.
JP2011033609 and JP2011059091 disclose an indoor position detector wherein three electromagnetic field sources are installed indoors to generate alternating magnetic fields having different frequencies. Again, US20120130632 discloses a system and method for locating, tracking, and/or monitoring the status of personnel and/or assets, both indoors and outdoors by deploying electromagnets.
Furthermore, DE10127156 discloses a local positioning system for moving objects including people, animals or vehicle to determine if the object is in danger and automatically dials a number. The position determination by the system is based on calculation of distance between a transmitter on the body of the object and a receiver. Such calculations can be complicated and lead to errors especially if the path taken by the moving object is not necessarily linear.
Still further, IN21220 discloses a container tracking system used to track shipping containers in a storage and transfer yard. Three dimensional accelerometers are provided on moving containers and position determination is based on direction of movement and acceleration magnitude information.
While indoor positioning systems known in the art can determine location of a person/object, need for a simple, accurate and robust system and method of localizing a moving subject is especially critical in emergency situations such as fire, water logging and the like to evacuate people from the indoor environment. As explained herein above the systems known in the art use geo-magnetic field distortions in the indoor environment for location detection which are susceptible to change due to change in indoor environment as well as weather conditions. Alternatively, electro-magnetic sensors used in these systems incur significant infrastructural changes and associated costs.
Thus there is a need for a system for locating a person or an object in an indoor environment that is free from disturbance due to environmental changes and from inertial navigation errors due to geo-magnetic field distortions and that can detect the orientation of the person/object.